Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Hi all, first time moped owner having some issues. Bought a cherry rebuilt 1977 Puch Maxi with the following mods.

• 70cc treat KIT

• 70cc hi hi compression head

• Tecno BOSS performance pipe

• 5 dellorto main jets - 80s range

• 5 dellorto main jets - 90s range

• Dellorto PHBG 21mm carburetor

• Malossi E12 air filter

• 19mm PHBG piston port intake

• Engine bearings and seals

• BLUE hi tension clutch springs

• E50 case allen bolts set

• Super stuffy racer crankshaft

• Domino grips

• Giuliari black TWO SEATER

• Passenger pegs

• Rear shocks

• Gold chain for both sides

• Brake pads

• Magura brake lever bolts

• All Cables

• Tubes and tires (sava MC1)

• Spark plug and spark plug boot

• Center stand kit

• EBR BLACK maxi forks WITH stabilizer + reinforced top plate

• MLM Reinforced swing arm

• Forks headset bearing set

• Headlight

• Petock, fuel line, and filter

• 17 tooth front sprocket, 41 tooth rear sprocket (comes with original 45t as well)

• Trail tech temp gauge and mount

• handlebars and mirrors

• Pedals

Had it for about a month road for about 35 miles with no problems at all. Easily hit 44 mph. Then recently very difficult to start, and drives for a bit then stalls up hills or after stopping at a light (read lots of threads have seen these problem). The other day drove for a bit then stalled. Wouldn’t start had to take a long walk home. When I came home let it sit then when I went to start it up it would idle really fast then die almost instantly.

Took off the Dellorto 21mm carb cleaned in with carb cleaning including all jets. The carb seemed really clean. Removed the 3 jets and soaked them sprayed everything down. Did notice the notch where the carb slide fits into had a bit of a chip and in the slide notch too. I sanded those down and it moved smoothly. Not sure if that would cause any issues. Changed out for new spark plug gapped properly. Tested spark has good blue spark. Bike has compression, and fuel seems to be flowing well. Cant test for leaks since I can’t get it to start and stay running.

Now the bike is very difficult to start. When it does start (rarely) it normally revs through the roof then stalls (5-10 seconds after starting) messed with the idle and mix screws with really no change.

Also think I have an issue with the throttle / cable. It doesn’t really snap back now after I cleaned the carb. When I take the air filter off I can see it operates but just doesn’t snap back. Opens with a little bump then slowly goes back but not really all the way. Sounds a bit like the cable rubbing against the carb slide spring when I pull back (might be normal-nothing to compare it to)

The guy I bought it off of is pretty far away but has been trying to help trouble shoot. Been watching videos, TONs of threads, Fred's guide, manuals. Just getting to the frustrating part and not knowing what to do. Any suggestions would be helpful.

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Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Photo of the bike - didn't attached on the first post somehow.

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Re: Puch 1977 - Hard to Start // Revs High // Stalls

Lubricate the throttle cable, it may be sticking in a position with the throttle slide open. When you see a throttle slide with that notch in it it can mean that the carb wasn't tuned correctly on the pilot jet, and to compensate the idle screw was hogged down all the way.

Also sounds like maybe an air leak or blown seal situation. Hard to say for sure, if you can get it to idle you should check for air leaks

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Thanks. I really want to check for air leaks but just cant get it to start. It ran so good for a while then just didnt. Going to remove the carb again. Would that imperfection in the slide / notch in the carb be an issue?

When I remove the fuel line from the carb and turn on the petcock how quickly / how much fuel should flow? I did it and it as a trickle then spitter a bit, should it be a steady flow until the petcock is turned off?

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Notch shouldn't be an issue unless it's causing the slide to stick. You should try maybe going up or down one size on the pilot once you get it running. What size jets are in there now?

The high revving could be from stuck open slide or from an air leak. If the slide isn't sticking open and you can't check for air leaks at idle because it won't idle, your options (in my opinion) are:

-mock up a leakdown tester and check for leaks that way (search function to find out how)

-Open up the magneto cover and see if there is any seepage coming from the seal behind the stator plate. If not, GENTLY tighten down the cylinder stud and intake nuts and carb mating clamp (check that the plastic shim is in there) and see if the situation improves, and if not order a new gasket set for the kit and maybe new seals for the crank

Re: Puch 1977 - Hard to Start // Revs High // Stalls

I'd clean that burr out of the slide channel and insure nothing sicks above the outside circumference of the slide . Also check the slide tunnel for any thing that might interfere with it's smooth operation .

With the petcock open there should be a steady stream of fuel .

Sounds like maybe the in tank screen could be clogged .

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Thanks both. I’ll work to clean the burr up a bit but it moves smoothly up and down. Hearing that I’m thinking might have some fuel starvation issues. Will pull the carb off tomorrow then see how much the fuel flows. Any guides around to work at cleaning the fuel flow?

Also are you familiar with the carb? The notch that fits into that slide channel is also damaged see photos.

Jet is an 82. I’ll need to pull out the others - don’t remember size off the top of my head.

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Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Also. When I removed the carb I feel like I screwed up the throttle cable. It moves with the air filter off you can see the slide in the carb move properly however the throttle isn’t super smooth ant the grip and doesn’t have a super clean snap back. Very slow and seems to only go back maybe 80-90 percent. Goes back when I move it manually and I also hold it closed when starting.

Having a hard time finding info on adjusting the throttle cable. Seems loose too me as the nuts and threaded sleeve just kind of hang near the throttle assembly on the bars - as if they don’t do anything. The cable itself just rests in the slot but if I pull it I could unseat it. (Photo after I pulled it out pretty easily) not sure if that’s normal or not.

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Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Main jet is 82. Choke/ starter is 60. Will need to pull out idle. Can’t remember that one.

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Re: Puch 1977 - Hard to Start // Revs High // Stalls

I'd take the burrs off that slide pin .

And , that throttle is definitely not right .

I'm not familiar with either the carb or the throttle , so I'm not much good for specifics .

You might consider taking the throttle tube off the bar and cleaning the inside , the cable catch /race , the housing inside and the bar . Then apply a dry graphite based lube to all friction surfaces , including the cable . Use enough lube in the cable until you see it coming out the other end .

Re: Puch 1977 - Hard to Start // Revs High // Stalls

your throttle has been mickey moused. get rid of that adjuster, theres a slot where the cable end slides into that lines up w the groove. i forget how puch throttle ties into grip buy get the right size knarp. on the carb. make sure u threading the cable correctly and have all the bits n pieces.

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

That photo was to demonstrate that if I tried - with not too much effort - I could pull the throttle cable out of the channel. I still think it’s a bit wonky since taking off the carb for the first time. Been having difficulty finding a ton of info about the proper way to set that throttle cable up. It’s on my list. (Photo shows normal)

But I agree the bit with the two bolts on the cable near the grip seems to do nothing. The part connecting to the carb seems proper.

Assuming I should just pull off the grip and take a look inside? Any easier way to do that?

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Re: Puch 1977 - Hard to Start // Revs High // Stalls

Alex Fredericksen /

That whole adjuster needs to go. It's for brake cables, not throttles. The cable housing should sit/tuck directly into the throttle. Adjusters for throttle cable go into carb side. You're gonna use something like the fucker in second pic 90% of the time.

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Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Thanks. My carb doesn’t have the metal elbow should it? Also are there different size throttle cables? Not length but gauge?(edited)

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Just pulled fuel line from carb. Turned on petcock. Nothing. Nothing comes out when on reserve either. What’s my next steps? Photo is with petcock open.

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Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Got fuel running through and was able to get it to start. Idles decent. When I give it throttle wants to stall. Let off throttle and it goes back to normal idle. If I pull the choke up on the carb it also wants to die. Any suggestions?

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Just buy a new petcock. They're cheap, and yours is obviously junk.

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Yeah how did you get the fuel to run through? Did you put more gas in the tank? Clean the petcock?

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Both. Petcock isn’t junk, just had a piece stuck.

The main problem now is that it starts will idle for hours. If I give it throttle or pull the choke up it dies out.

Does that make it lean or rich?

Going to pull the carb and check everything again. Then play with carb adjustment screws.

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Sounds like it could still be restricting flow, thus providing enough fuel to idle but not run at higher fuel demand.

Does that make it lean or rich

Yes.

Then play with carb adjustment screws

It only has an idle screw. That probably won't help.

You already determined you have a fuel flow problem. If your petcock is now fine, your carburetor is probably dirty, because if the petcock had junk in it, it let junk into the carb.

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Actually that carb has a fuel screw as well. It's designed to help fine tune the idle and off-idle mixture.

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Bingo. Have to toy with both. I have the fuel mix screw all the way in. If I back it out it runs like it’s going 35,000 miles an hour. Going to take off carb again and make sure everything is good and the float isn’t getting stuck etc. leaned it last week and it was sparkling.

Re: Puch 1977 - Hard to Start // Revs High // Stalls

General rule of thumb is that the fuel mixture screw should be around 2.5 turns out (if i remember correctly.) all the way closed means the idle jet is too rich. this may be why the P.O. had the slide adjustment idle screw cranked all the way in too

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Carb slide is stuck. Taking apart to see why now!

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Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Throttle cable not attached correctly to the carb slide. Any guides on how to do this properly?

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Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Assuming carb slide end with most room houses the spring. Ok goes in from that side first. See a hole. Throttle cable or white numbe goes in there? Hmmm

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Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Guessing only throttle cable goes all the way through the slide then shifts over and locks. White nun has nothing to do with it. Kind of a pain to do with spring.

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Got cable hooked up properly. Starts right up but rips pounder harder and faster then I’ve ever heard. I shut it down. Idle screw is about 2 1/4 turns out. Mixture screw all the way in.

Suggestions?

Re: Puch 1977 - Hard to Start // Revs High // Stalls

Tyler Durphine /

Thinking the carb slide isn’t closing all the way so when I crank it it’s just ripping. It slides up and down freely. Possible the needle isn’t set correctly or needs adjusting? Hesitate to adjust needle since it ran for a good while fine with that before issues started. Both mix and idle screws do nothing. Here’s photo with no throttle.

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Re: Puch 1977 - Hard to Start // Revs High // Stalls

Cable looks too short. Possibly hanging up somewhere

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